The invention relates to a torsional vibration damper for taking up and/or compensating for rotary shocks, especially torque fluctuations of an internal combustion engine, with at last two disc parts which are rotatable relative to each other against the action of at least one energy accumulator which is provided between the disc parts in the force transmitting path and acts at least in the circumferential direction.
Torsional vibration dampers of such kind are known and in accordance with one embodiment, can constitute divided flywheels with flywheel masses. Torsional vibration dampers of such kind normally comprise circumferentially spaced apart energy accumulators which are biased on the circumferential side through recesses or shaped areas in the two flywheel masses. By way of example, reference is made to FR PS 2 166 604. Such torsional vibration dampers are subject to pronounced wear upon the biasing devices and energy accumulators as a result of their design. Solutions have therefore been proposed such as, for example, in DE PS 35 15 928 using lubricant-filled energy accumulator chambers which are sealed on the outside but these are correspondingly expensive to construct and therefore involve increased manufacturing costs.
Accordingly, it is an object of the invention to provide a torsional vibration damper of the kind described which is less susceptible to wear and thus exhibits a greater durability whilst at the same time optimizes production costs. Furthermore, a simple mounting of the energy accumulators in the flywheel masses is also to be made possible. The energy accumulators should be supported as uniformly as possible at their ends in the circumferential direction and secured against escape radially outwards in the event of high centrifugal forces.
This is achieved according to the invention by the provision of a torsional vibration damper which comprises between at least two relatively rotatable disc parts at least one energy accumulator in the force transmitting path, which is active at least in the circumferential direction, and which is housed in a suspension device divided into two socket parts, the two socket parts being adapted to be biased in dependence on the circumferential direction by biasing means of the two disc parts to compress at least one energy accumulator and the biasing devices each bias one socket part alternately in dependence on the direction of rotation.
Torsional vibration dampers of such kind can be equipped for example with simple disc parts and can be used as friction lining supports in a clutch, for example, in the power train between the drive unit and the gearbox. Furthermore, the disc parts can be provided with flywheel masses or can consist of flywheel mass elements whereby they can be used in the power train as a divided flywheel with two flywheel masses which can be rotated relative to each other against the action of the at least one energy accumulator.
The biasing means can advantageously be shaped as a bolt or stud fixed axially on the disc parts, and the disc parts can constitute circular discs and can be provided with flywheel masses and one disc part can be connected to the drive shaft of an internal combustion engine and the second disc part can be connected to the input shaft of a gearbox through a friction clutch or the like fixed on the second disc part.
The suspension or receiving device, which can also be used in conventional damping devices without flywheel masses, consists for suspension of the at least one energy accumulator, wherein four to eight, and preferably six, helical compression springs spread out over the circumference can be particularly advantageous, of two socket parts which for reasons of cost efficiency and easier mounting can be identical and face one another mirror symmetrically and can be fitted in each other turned by the angle of one energy accumulator socket whereby in the event of predetermined stressing they can transmit a basic friction torque in the torsion vibration damper at the points where they contact each other. Furthermore, stops or sockets for the energy accumulator corresponding to the relevant number of energy accumulators can be provided on each socket part and extend over the entire axial width of the suspension device and therefore engage in the relevant other socket part so that for each energy accumulator one stop or one biasing device can be formed at one circumferential end by the first socket part and thus by the first disc part and at the other end by the second socket part and thus by the second disc part. The large surface socket can advantageously be 70% and more of the area of the energy accumulator cross-sections and, therefore, the ends of the energy accumulators need not be ground as exactly flat as in conventional dampers or indeed grinding can be omitted completely. The inclination of a socket in the circumferential direction is preferably selected in such a way that it conforms to the inclination of the ends of the energy accumulators and thus the contact faces of the energy accumulator ends can be further optimized.
According to the invention, the two preferably identical socket parts are formed in such a way that they each have a ring-shaped carrier mounted at the outer circumference and a ring shaped support mounted on the inner circumference which both lie in one plane and have approximately half the axial width of the suspension device whereby on one axial side the sockets provided radially between the support rings protrude for the energy accumulators which when the two socket parts are assembled engage in each other. The outer support can have approximately the cross-sectional shape of a quarter circle or can be chamfered so that the suspension device overall can have approximately a semi circular profiled section or a profiled section on the outer circumference which is chamfered at the outer edges.
It can further be advantageous to limit the extent of angular movement of the two socket parts, that is the angular movement of the socket parts relative to the biasing means of the disc parts. To this end, in addition to the blocking of the energy accumulatorsxe2x80x94when using coil compression springs through the windings stopping against each otherxe2x80x94stops can be provided on the sockets for the energy accumulators inside the outer support and these project circumferentially into the pockets in which the energy accumulators are housed whereby of each socket of the energy accumulator one stop projects into the pocket so that by selecting the length of the two stops projecting into the pockets it is possible to fix the turning angle in the circumferential direction. A turning angle is preferably selected which is smaller than that provided by the blocking of the energy accumulators.
The stops which are provided to limit the extent of angular movement advantageously serve at the same time as radial supports for the energy accumulators radially outwards, especially in the case of high centrifugal force action, and to this end can have the cross-section of a ring segment. A profiled section matching the cross-section of the energy accumulators can be formed as a support for the energy accumulators on the inside in the area of the pockets for holding the energy accumulators on the inner support whereby the overall profiled section is produced by fitting together the two supports of the socket parts. The inner circumference of the two inner supports can be designed flat so that the hanging device where required can be centered and/or mounted thereon.
When using coil compression springs as energy accumulators these can be wound according to the invention so that they have windings with different diameters. Coil compression springs can advantageously be used which starting and ending with a winding of larger diameter have alternately large and small windings. Furthermore it can be provided that the center point axis of the windings with large and small diameter is not the samexe2x80x94thus a concentric arrangement of the windings along the axial extensionxe2x80x94but that the center point axis of the windings with smaller diameter is displaced parallel to the center point axis of the large windings so that on one side of the winding circumference the windings of small diameter can be inserted in the inner circumference of the windings of large diameter and on the other side can be mounted at the same radial height. An installation position of the coil springs can be advantageous with the insertable windings of small diameter on the outer circumference of the suspension device so that the radially larger compression path of the springs can be compensated for and the spring capacity can be optimized whereby the springs can be suspended in the corresponding sockets so that rotation is prevented. Springs of this kind can advantageously be used also in many other cases, for example, in disengagement devices as over dead center springs, compensation springs and/or return springs and the like.
Further sockets or openings can be provided at the sockets for the energy accumulators facing away from the socket faces for engagement of the biasing means of the flywheel masses. The biasing means of the disc parts advantageously consist of bolts engaging axially in a socket part for which half-shell shaped openings are impressed on the side of the energy accumulator sockets opposite the receiving faces for the energy accumulators and these openings form with the second socket part an approximately circular opening in which an axially aligned biasing meansxe2x80x94here preferably boltsxe2x80x94of each disc part can enter without contacting one another. Therefore, during rotation of the two disc parts relative to each other, the two socket parts can be turned in the relevant direction of rotation of the disc parts and the energy accumulators can thereby be compressed about their neutral position by each disc part. This can lead to a more even biasing of the energy accumulators and thus to reduced wear, especially in the case of high speeds with corresponding centrifugal force action and with energy accumulators which are stretched in the circumferential direction accordingly.
In order to shield the suspension device from the action of the centrifugal force and/or to protect the suspension device from thermal stressing by the disc partsxe2x80x94particularly in the case of disc parts having flywheel masses of a divided flywheel which is connected to the output side on account of the ensuing friction heat through the clutch which can be attached herexe2x80x94the suspension device can be provided on its outer circumference with a corresponding reinforcement made for example of a heat-reflecting and/or tension-resistant material such as metal whereby this reinforcement can follow the surface profile of the outer support and can surround same over the entire circumference in cross-section approximately semi-circularly or chamfered over the outer edges or a reinforcement can be provided for each support, by way of example, by means of two circumferentially complete wire rings on the outer circumference of each support whereby a circumferential groove can be formed in the supports to guard against axial slipping of the rings.
Advantageously the suspension device is made from a plastic material whereby injection moulding processes are preferably used although a design of metal can also be advantageous.
The suspension device can be arranged for an ideal formation of the energy accumulators over the entire radius of the torsional vibration damper whereby advantages are gained when mounted in the area radially outside of the fastening screws of the first disc part on the drive shaft of the internal combustion engine, especially directly at the circumference of this screw circle.
The torsional vibration damper according to the invention can be fitted with a friction generating device acting in the range of the angular displacement between the two disc parts and which can include a base friction and/or a selected variable friction whereby the selected variable friction can be controlled by means of a friction control disc which can engage in a disc part or in a component part fixedly connected thereto and acts on a friction disc which is fixed securely on the other disc part or a component part connected to same whereby an intended turning play between the friction control disc and the disc part can cause a delayed friction. In this way a friction generating device can be designed so that the friction control disc engages by axially protruding teeth, preferably formed on its outer circumference, in recesses of one of the two disc parts, preferably in the force applying componentxe2x80x94by way of example in the divided flywheel connected to the drive shaftxe2x80x94whereby the friction generating device can be mounted radially outside or radially inside the suspension device. The friction disc is advantageously inserted or snap-fitted by axially protruding studs rotationally secured on the other disc part preferably the one connected to the gearbox side or emitting the force. It can be further advantageous to make the friction force dependent on the force being applied to the energy accumulator, thus in dependence on the spring force in the case of coil compression springs. To this end, one side of the torsional vibration damper, for example, the side of the first flywheel mass can be fitted with conical biasing means which are placed against complementary conical sockets of the socket part and thus form a ramp. The friction disc is mounted axially between the flywheel mass and the energy accumulator sockets and can be placed in the neutral position of the energy accumulators friction-free or with a predetermined basic friction. If relative rotation takes place between the flywheel masses through biasing of the energy accumulators, then the socket part with the socket of the energy accumulators is moved along the ramp in dependence on the force being applied to the energy accumulators axially in the direction of the friction disc and thus the friction force is correspondingly increased.
A further inventive concept contemplates the provision of a torsional vibration damper whose biasing means are formed directly on, for example integral with, a disc part or a component part connected therewith. For example, it can be advantageous to design the biasing means of a disc part mounted on the gearbox side with a flywheel mass of axially aligned extension arms of the clutch cover fixed on the disc part or on the flywheel mass and/or to provide the biasing means on the drive side as radially aligned stops or a window recessed in the disc part according to the spatial extension of the energy accumulator.
Furthermore it can be advantageous to use a slip clutch which can have preferably a restricted turning angle. The slip clutch can be provided between a disc part on the gearbox side or drive side, preferably connected on the gearbox side, and the associated flywheel mass whereby the turning angle is restricted by recesses in the flywheel mass forming stops, in which corresponding extension arms of the disc part can be moved between two stops against the action of the friction force of the slip clutch. The friction devices establishing the friction force of the slip clutch can be mounted on the side of the disc part or flywheel mass facing the gearbox and/or internal combustion engine, for example, radially inside the friction face for the shift clutch and/or at the rear side of the flywheel mass formed as a contact pressure plate.
A further inventive concept involves the provision of an arrangement of several but at least two suspension devices radially spaced from each other so that two independent damping devices are formed which can be combined with each other and which can be formed in two stages or are designed for the purpose of increasing the torque which is to be damped and/or transmitted. Furthermore, it is conceivable that a suspension device be combined with a damping device fitted radially on the outside, for example in series connection, which has as energy accumulators in the form of curved springs and which can be filled with lubricant. Furthermore, it can be particularly advantageous for producing a particularly long-running torsional vibration damper to also grease or oil the hanging device or to operate same confined in a chamber in lubricating medium such as grease or oil or the like.